86 ERYTHEA. 



Northwardly JR. lanceolata does Dot appear to range beyond 

 the forty-second parallel, while to the southward it hardly 

 passes the thirty-fifth, except as reaching northeastern Texas. 

 It is an inhabitant of dry grounds, preferring rocky hillsides; 

 thus, in point of habitat as in other particulars, very unlike 

 its next of kin. The species is supposed to embrace the R. 

 Shortii of Nuttall, and R. parvifoliiis of Torr & Gray; though 

 Nuttall was very positive that his species was distinct from 

 it, and the matter may need further investigation. 



2. K. ALNIFOLIA, L'Her. Sert. Angl. 5. This common and 

 widely dispersed shrub of cold northern swamps is most un- 

 like the preceding in its thin and very conspicuously pinnate- 

 veined leaves; the venation of R. lanceolaia not being in any 

 wise prominent. It is in equally marked contrast with the 

 type of Rhamnus, i. e. R. cathartica, the venation of the 

 leaves of which is almost wholly longitudinal and parallel, as 

 well as very prominent. These characters taken in conjunc- 

 tion with pyriform berries, the thin soft seed-like texture of 

 the pyrene, and its cuneate-obovate outline, furnish some- 

 thing like a justification for Rafinesque's proposal to consti- 

 tute this a genus, Girtannera. The species is, nevertheless, 

 technically congeneric with R. lanceolata^ whether naturally 

 so or not. In its eastern distribution it barely overlaps with 

 R. lanceolaia fi the northern limit of that species, and thence 

 extends northward over at least ten degrees of latitude, and, 

 along the British boundary runs westward to the most north- 

 westerly extension of the Rocky Mountains, then passing 

 southward along the eastern declivity of the Cascades and 

 Sierra Nevada to near the headwaters of the Truckee River. ^ 

 It thus becomes the only Rhamnus^ which almost traverses 

 the continent; and, at its western limit it is curious to note, 

 that it conforms to the law of distribution there dominant, 

 running southward for some hundreds of miles in an ex- 

 tremely narrow belt. 



